WASHINGTON (NBC) - President Obama takes the public oath of office today in front of an estimated 800,000 people at the Capitol Building shortly before noon today. Today's inauguration is strictly ceremonial. Yesterday's private inauguration at the White House was the official start of President Obama's second term in office, as mandated by the Constitution.

President Obama took the oath, placing his hand over a Bible belonging to First Lady Michelle Obama's family. He was surrounded by just family for Sunday's inauguration.

Today's inauguration is full of symbolism, with President Obama placing his hand on both Martin Luther King, Junior's Bible and Abraham Lincoln's Bible, while he takes the oath of office. This, while he faces the Lincoln Memorial where Dr. King delivered his "I Have a Dream Speech" nearly 50 years ago.

This year's inaugural poet is Richard Blanco, who lives in Bethel, Maine, but was born in Spain to Cuban exiles. Blanco will be the first Latino and openly gay person to speak at an inauguration.

Like most president's second-term inaugural address, President Obama's speech is expected to outline his goals for the next four years in office.

Around 2PM, the Obama and Biden families will join groups from around the country for the Inaugural Parade. The Gym Dandies, a unicycling group from Scarborough, will ride their 6' unicycles in the parade.

The day wraps up with the Inaugural Ball, which begins at 6PM and honors members of the service.